It is known in that art that there are many compounds which can act as a disinfecting agent. For example, solutions of 70–85% (volume/volume) ethanol are commonly used as disinfectants. As is known in the art, there are two forms of ethanol generally available in North America: denatured ethanol, and potable alcohol. Both denatured and potable ethanols are used in the preparation of the solutions noted above. Denatured ethanol contains additives for the purpose of preventing or reducing abuse or consumption of the alcohol. Such additives may include aviation fuel, emetics, various organic solvents and mercury salts. Bitrex is an example of an additive that is commonly present in ethanol in varying amounts. For instance, bitrex is present in specially denatured alcohol grade-3 (SDAG-3) at 700 mg per 100 liters, and is present in specially denatured alcohol grade-6 (SDAG-6) at 1 g per 100 litres. Solutions of 70–85% ethanol are effective in inactivating most vegetative bacteria, fungi, and lipid containing viruses. However, ethanol is not effective against bacterial spores.
As noted above, disinfecting agents vary in their ability to kill different microorganisms. For example, some compounds may act as a bactericide only, other as a virucide only, and yet others as a fungicide only. Some compounds are known which may kill gram-positive bacteria, yet not be effective in killing gram-negative bacteria. Accordingly, a disinfectant that can effectively kill most, if not all microorganisms may require a combination of known disinfecting agents with complementary activity in order to provide a wide spectrum disinfectant.
Combinations of disinfecting agents can compound the risks associated with the use of any of those agents individually. Due to interactions between disinfecting agents, the combination may introduce new hazards in use, such as reduced efficacy of the disinfecting agents, irritation to the user, environmental risks such as flammability, and reduced residual effects of the disinfecting agents.
U.S. Reissue Pat. No. 32,300 describes the use of anti-microbial agents in combination with polyethylene glycol as a skin cleansing composition. The polyethylene glycol is used as a sudsing agent and lacks any anti-microbial properties. The anti-microbial agents suggested in that reissue patent have limited efficacy. In particular the combination described lacks tuberculocidal activity and has limited anti-viral activity. Further, the anti-microbial agents described in that reissue patent lose anti-microbial activity unless they are maintained in a non-ionic environment.
Canadian Patent No. 1,290,250 relates to an antiseptic fluid which, upon drying forms a skin protective film with residual anti-bacterial properties. The residual activity of the fluid described is dependent on a disposable film forming a polymer carrying specified bactericides. Due to its limited spectral efficiency the film is limited in the scope of its application and is not suitable for use in high infection risk environments.
Canadian Patent No. 1,332,136 describes the use of relatively high concentrations of a chlorhexidine salt complexed with a non-ionic surfactant in order to maintain a bactericidal activity, particularly against Staphylococcus aureus. However, chlorhexidine salts, such as chlorhexidine gluconate, in the relatively high concentrations described in Canadian Patent No. 1,332,136 irreversibly stains.
U.S. Pat. No. 5,030,659 describes an aqueous disinfectant using a combination of microbicidal compounds in specified ratios to broaden the spectrum of the anti-microbial activity. However, that disinfectant uses relatively high relative concentrations of benzalkonium chloride. The disinfectant described also lacks a denaturant or a cleanser resulting in a loss of potential disinfecting capacity. Further, at some concentrations of ethanol proposed in this patent, the disinfectant described is also combustible.
Canadian Patent No. 1,335,352 describes an oral bactericidal solution intended to prevent or inhibit growth of bacteria on tooth surfaces. The solution described includes at least one polymer which has one or more pendant polyalkylene oxide groups. It is stated that this solution enhances the anti-adhesive and antibacterial properties of tooth surfaces with a reduced risk of staining with chlorhexidine. However, it is not suggested that the solution has a broad spectrum of activity, or that it can act as a virucide or fungicide. Accordingly, the solution may be limited in its application to tooth surfaces.
U.S. Pat. No. 5,985,931 describes the use of a combination of anti-microbial agents in an aqueous solution to achieve a synergistic effect of the component anti-microbial agents. This solution suffers from a numbers of limitations. First, since the solution is about 70% water it will have some corrosive properties. Second, and notwithstanding any synergistic effects, the spectrum of organisms which the component anti-microbial agents can kill is not suggested to be broader. Accordingly, the solution will not be suitable for many uses required in a hospital grade product as it will not significantly reduce or kill Mycobacterium tuberculosis, and is of only limited utility in killing gram-negative bacteria and fungi.
Canadian Patent Application No. 2,132,688 describes a formulation that can act as a spermicide and virucide using a combination of benzalkonium chloride and nonoxynol. The purpose of the described formulation is as a vaginal application to protect against transmission of sexually transmitted viruses and other infections and to protect against conception. There is no suggestion in the description that this formulation has a broad spectrum of activity as a fungicide or bactericide. Further, there are some health concerns regarding the use of relatively high concentrations of nonoxynol and the possibility that nonoxynol when applied vaginally, may cause vaginal ulcerations.
Canadian Patent Application No. 2,309,353 describes an aqueous solution containing up to 20% by weight of a surfactant, and an anti-microbial quaternary ammonium compound. The anti-microbial activity of this solution is limited by the efficacy of the quaternary ammonium compound sued. In addition, the high aqueous level can render the product corrosive and thus limit its use to skin, nail, mouth and mucous membrane applications.
U.S. Pat. No. 4,870,108 describes a liquid antiseptic containing ethanol, acetone, glycerin, water, and a quaternary ammonium compound. This antiseptic is said to be rapid acting and non-irritating to skin after repeated use. However, there are problems with the use of the components of this liquid. Glycerin in the antiseptic prohibits the use of the solution on hard surfaces, instruments, and in high-risk areas. This antiseptic has limited residual anti-microbial activity, and for example, is not tuberculocidal. Further, the combination of acetone with ethanol is extremely flammable, and thus may present a safety risk in use.
Canadian Patent No. 2,023,287 describes the use of a combination of alcohols including benzyl alcohol to provide a broad spectrum antimicrobial composition. The specific combination of alcohols is said to have a lowered flash point when compared to previously available mixtures while providing synergistic effects on antimicrobial activity. However, the formulation suffers from the disadvantage that it is quite toxic and is not suitable for hospital grade disinfection. Further, the combination described is also water and moisture sensitive.
U.S. Pat. No. 5,800,827 describes compositions using an organic acid, with chlorhexidine in ethanol in concentrations greater than 50% by weight. The organic acid is believed to stabilize the chlorhexidine in the ethanol while maintaining the germicidal activity of the chlorhexidine. The organic acids described to stabilize the chlorhexidine are lactic acid and citric acid. However, while the chlorhexidine is stabilized, its spectrum of activity is unchanged. Thus, the compositions described are limited to the spectrum of activity of the chlorhexidine.